Merge #11878: Add Travis check for duplicate includes

c36b720d00 Add Travis check for duplicate includes (practicalswift)
280023f31d Remove duplicate includes (practicalswift)

Pull request description:

  This enforces parts of the project header include guidelines (added by @sipa in #10575).

  Example run:

  ```
  $ git diff
  diff --git a/src/warnings.cpp b/src/warnings.cpp
  index c52a1fd..d8994dd 100644
  --- a/src/warnings.cpp
  +++ b/src/warnings.cpp
  @@ -5,6 +5,8 @@

   #include <sync.h>
   #include <clientversion.h>
  +#include <string>
   #include <util.h>
   #include <warnings.h>
  +#include <util.h>

  diff --git a/src/warnings.h b/src/warnings.h
  index e8e982c..8d2252e 100644
  --- a/src/warnings.h
  +++ b/src/warnings.h
  @@ -7,6 +7,7 @@
   #define BITCOIN_WARNINGS_H

   #include <stdlib.h>
   #include <string>
  +#include <stdlib.h>

   void SetMiscWarning(const std::string& strWarning);
  $ contrib/devtools/lint-includes.sh
  Duplicate include(s) in src/warnings.h:
  #include <stdlib.h>

  Include(s) from src/warnings.h duplicated in src/warnings.cpp:
  #include <string>

  Duplicate include(s) in src/warnings.cpp:
  #include <util.h>
  $ echo $?
  1
  $ git checkout .
  $ contrib/devtools/lint-includes.sh
  $ echo $?
  0
  ```

Tree-SHA512: f653d23c58ebc024dfc5b1fb8570698fd3c515c75b60b5cabbc43595548c488fca92349fa4c8b64460edbe61c879ff1d24f37f959e18552e202a7342460ddbf1

1 files changed, 0 insertions, 1 deletions

diff --git a/src/interfaces/handler.cpp b/src/interfaces/handler.cpp
index 1443fe9f18..8e45faa2a5 100644
--- a/src/interfaces/handler.cpp
+++ b/src/interfaces/handler.cpp
@@ -7,7 +7,6 @@
 #include <util.h>
 
 #include <boost/signals2/connection.hpp>
-#include <memory>
 #include <utility>
 
 namespace interfaces {